title: Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians.
abstract: Population declines and extinctions of amphibians have been attributed to the chytrid fungus Batrachochytrium dendrobatidis (Bd), especially one globally emerging recombinant lineage ('Bd-GPL'). We used PCR assays that target the ribosomal internal transcribed spacer region (ITS) of Bd to determine the prevalence and genetic diversity of Bd in South Korea, where Bd is widely distributed but is not known to cause morbidity or mortality in wild populations. We isolated Korean Bd strains from native amphibians with low infection loads and compared them to known worldwide Bd strains using 19 polymorphic SNP and microsatellite loci. Bd prevalence ranged between 12.5 and 48.0%, in 11 of 17 native Korean species, and 24.7% in the introduced bullfrog Lithobates catesbeianus. Based on ITS sequence variation, 47 of the 50 identified Korean haplotypes formed a group closely associated with a native Brazilian Bd lineage, separated from the Bd-GPL lineage. However, multilocus genotyping of three Korean Bd isolates revealed strong divergence from both Bd-GPL and the native Brazilian Bd lineages. Thus, the ITS region resolves genotypes that diverge from Bd-GPL but otherwise generates ambiguous phylogenies. Our results point to the presence of highly diversified endemic strains of Bd across Asian amphibian species. The rarity of Bd-GPL-associated haplotypes suggests that either this lineage was introduced into Korea only recently or Bd-GPL has been outcompeted by native Bd strains. Our results highlight the need to consider possible complex interactions among native Bd lineages, Bd-GPL and their associated amphibian hosts when assessing the spread and impact of Bd-GPL on worldwide amphibian populations.
authors.affiliation: Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul, 151-747, South Korea.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bataille
authors.affiliation: Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul, 151-747, South Korea.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Fong
authors.affiliation: Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul, 151-747, South Korea.
authors.forename: Moonsuk
authors.initials: M
authors.lastname: Cha
authors.affiliation: Museum of Vertebrate Zoology, University of California, Berkeley, CA, 94720, USA.
authors.forename: Guinevere O U
authors.initials: GOU
authors.lastname: Wogan
authors.affiliation: Conservation Genome Research Bank for Korean Wildlife, College of Veterinary Medicine, Seoul National University, Seoul, 151-742, South Korea.
authors.forename: Hae Jun
authors.initials: HJ
authors.lastname: Baek
authors.affiliation: Conservation Genome Research Bank for Korean Wildlife, College of Veterinary Medicine, Seoul National University, Seoul, 151-742, South Korea.
authors.forename: Hang
authors.initials: H
authors.lastname: Lee
authors.affiliation: Conservation Genome Research Bank for Korean Wildlife, College of Veterinary Medicine, Seoul National University, Seoul, 151-742, South Korea.
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Min
authors.affiliation: Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul, 151-747, South Korea.
authors.forename: Bruce
authors.initials: B
authors.lastname: Waldman
mesh_terms: D000663:Amphibians / Q000382:microbiology; D000818:Animals; D000835:Animals, Wild / Q000382:microbiology*; D001001:Anura / Q000382:microbiology*; D008411:Chytridiomycota / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D021903:DNA, Ribosomal Spacer / Q000032:analysis / Q000235:genetics; D014644:Genetic Variation; D006239:Haplotypes; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D009181:Mycoses / Q000382:microbiology / Q000662:veterinary*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D056910:Republic of Korea; D017422:Sequence Analysis, DNA; D014562:Caudata / Q000382:microbiology*
chemical_list: D021903:DNA, Ribosomal Spacer
keywords: chytrid fungus; conservation; emerging infectious disease; endemism; frogs; host-parasite co-evolution; invasive species; population declines; prevalence; salamanders